Method of grinding glass



W. TAYLOR.

METHOD or GRINDING GLASS. 7 APPLICATION FILED OCT. 28, 1920.

v 1,401,830. Patented Dec. 27, 1921.

ATTORNEY cairn WILLIAM TAYLOR, OF LEICESTER, ENGLAND.

METHOD OF GRINDING GLASS.

Specification of Letters Patent.

Original application filed October 28, 1916, Serial No. 128,235. Dividedand this application filed October To all whom it may 22 061% Be itknown that I, lVILLmiLTAYLoR, a citizen of Great Britain. residing atLeicester, in the county of Leicestershire. England, have inventedcertain new and useful Improvements in Methods of Grinding Glass, fullydescribed and represented in the following specification and theaccompanying drawing, forming a part of the same.

This invention relates to 'a method of grinding glass and the like. Thisapplication is a division of my co-pending application, Serial No.128,235, filed October 28 1910, and is directed particularly to a methodfor grindinga spherical surface. An object of the invention is toprovide for rapidly forming a'spherical surface upon a glass blank. Themethod is particularly adapted-to the grinding of lenses which are tohave a deep convex curve.

The accompanying drawing illustrates diagrammatically the carrying outof the method. grinding is done by a cup-shaped wheel, 3 mounted forrotation about an axis a-b.

The lass disk 1 to be ground is carried by. a spi dle 2. The axes of thespindle 2 and the grinding wheel 3 are mounted so as to lie in the sameplane. The axis of the work spindle 2 is so mounted that it may be swungabout-an axis C intersecting the spindle axis at a point which is thecenter of the spherical surface to be formed, and preferably at rightangles to the common'plane of these axes.

In carrying out the method of grinding, the work spindle is swung slowlyto carry the work past the rapidly moving grinding edge of the wheel,preferably so that the grinder attacks first the periphery of the diskand grinds inwardly toward the center. Usually the work spindle isrotated in a direction'to cause the work at the place of contact withthe grinding wheel to move in the opposite direction to the movement ofthe grinding wheel at this point. The rotation of the work is desirablyat a comparatively low speed, for example, about 100 revolutions perminute for grinding glass disks one inch in diameter.

The grinding edge of the cup-shaped- As shown in the drawing, the

Serial No. 4201176.

side of. the step formed in the glass is substantially perpendicular tothe finished or ground surface of the lens or to the shifting tangent tosaid surface, throughout the operation, but it is perpendicular to theoriginal flat surface of the disk only at the.

end of the operation at the center of the lens where the depth of the,step is relatively small. In the. early stages of the operation, theoriginal surface of the disk forms, as seen in the drawing, an acuteangle with the side of the step, and the consequent.

fragility of the side of the step here facilitates the removal of theglass and enables the wheel to attack successfully a deeper step than itotherwise could.

In. the operation descrlbed the grindingis done upon the side of thecircular step,

the wheel contacting with the-surface formed at the base of the steponly. By the method described a deep'spherically curved surface isground on the work by a single cut even when the. blank upon which theoperation takes place has at the beginning of the operation a fiatsurface or other surface not conforming to the desired spherical face.The method thus affords an extremely rapid and eflici-ent means forgrinding a spherical surface upon glass blanks,

I wish it clearly understood that my invention is by no means limited tothe specific procedure described in connection. with the accompanyingdrawing as illustrative of the invention.

Vhat is claimed is:

1. The method of grinding a convex -spher-' ically curved surface upon aflat disk of glass, which comprises rotating the disk upon an axispassing through'the surface to be ground, forming in the surface to beground a circular step having its center on, the axis of rotation of thedisk, grinding back said step to said axis by bringing successiveportions of the side of the step into contact with a grinding surfacemoving along the portion of the side of the step with which it is incontact, and decreasing the depth of the step as it is ground inwardlyWhile varying the angle of the side of-said step to the originalsurface. of the disk so that it is acute at the beginning of theoperation and substantially a right angle at the end of the operation.

2. The method of grinding a desired surface on a glass blank having asurface not conforming to the desired surface to be formed, whichcomprises rotating the glass blank upon an axis passing through saidsurface, forming in said surface a circular step having its center onthe axis of rotation of the blank, \and grinding back said stepcontinuously from the periphery to the cen- \VILLIAM TAYLOR.

' Witnesses -MA1s1n MAURUs, LILLIAN R. Fox.

